A vertebral spreading instrument is known, for example, from U.S. Pat. No. 6,478,800 B1, the disclosure of which is incorporated herein by reference in its ventirety. As disclosed in U.S. Pat. No. 6,478,800, two vertebrae can be spread by two fingers or blade tips and, via a sliding or pusher rod, an artificial intervertebral disc can be slid between the blade tips and into the free space created by spreading the vertebrae. Thus, U.S. Pat. No. 6,478,800 B1 discloses a possible embodiment of a spreading mechanism that operates such that the two spreading fingers or blades are each extensions of a lever arm that can be pivoted about a common bearing. The artificial intervertebral disc can be pinched between the two lever arms and situated distal to the bearing, wherein the lever arms reduce their distance in the distal direction.
The distance between the lever arms thus becomes smaller as they are situated closer to the spine. If the distal intervertebral disc then is shifted further in the distal direction, it thus forces the two lever arms apart. This results in two vertebrae of the intervertebral discs being spread, such that the artificial intervertebral disc can be slid into a free space between the two vertebrae by the spreading fingers or blades. The free space between the vertebrae is a result of a previously performed surgical removal of the damaged intervertebral disc.
A vertebral spreading instrument also is known from U.S. Pat. No. 6,261,296 B1, the contents of which is incorporated herein by reference in its entirety. The vertebral spreading instrument includes a scissor-like vertebral spreading mechanism, wherein two limbs or extensions are arranged such that they can rotate about an axis (e.g., an axis formed by a bolt coupling the extensions together), thereby providing a scissor-like motion. Proximal handles diverge in the proximal direction, and by pressing the handles together, spreading fingers at the distal end of the scissor-shaped spreading instrument move apart as the extensions rotate about the axis. The distance between the spreading fingers can be set at the proximal end of the spreading instrument via a setting screw that connects the two handles at the proximal end of the spreading mechanism.